On-line advertisements (or “ads”) allow advertisers to reach a wide range of viewers through the Internet. Sponsors of ads may use intuition and past experiences to determine which audience to target. The sponsors are often interested in increasing the effectiveness of the ads. Some sponsors use post-campaign ad effectiveness studies to aid in determining the effectiveness of the ads. The reports may show, for example, whether online user behavior as manifested by web site visitations and search activity have increased due to the display of ads. The experience gained in one ad campaign may be used in designing future ad campaigns.